I have been playing with MDNS recently, and using the ZeroConf Browser as a way to explore the services on my local network. I discovered that if I try to see the details for a service (i.e. from the associated "SRV" and "TXT" records) whose instance has an underscore character embedded in its name, the details are not shown. Instead, after a short while, I usually get a message that says "Not available" or nothing at all. An example of such a service is "ESP_DF103F._arduino._tcp.local". If I change the name to "ESP-DF103F._arduino._tcp.local" (i.e. the embedded underscore has been replaced with a dash), then the ZeroConf Browser is able to show the service's details as expected.